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Open Access Research article

Biochemical and molecular heterogeneity among isolates of Yersinia ruckeri from rainbow trout (Oncorhynchus mykiss, Walbaum) in north west Germany

Yidan Huang1, Martin Runge2, Geovana Brenner Michael3, Stefan Schwarz3, Arne Jung4 and Dieter Steinhagen1*

Author Affiliations

1 Fish Disease Research Unit, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany

2 Lower Saxony State Office for Consumer Protection and Food Safety (LAVES), Food and Veterinary Institute Braunschweig/Hannover, Hannover, Germany

3 Institute of Farm Animal Genetics, Friedrich-Loeffler-Institute (FLI), Neustadt-Mariensee, Germany

4 Clinic for Poultry, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany

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BMC Veterinary Research 2013, 9:215  doi:10.1186/1746-6148-9-215

Published: 21 October 2013

Abstract

Background

Enteric Redmouth Disease (ERM), caused by Yersinia ruckeri, is one of the most important infectious diseases in rainbow trout (Oncorhynchus mykiss) aquaculture in Europe. More recently, non-motile vaccine resistant isolates appear to have evolved and are causing disease problems throughout Europe, including Germany. The aim of this study was to analyse the variation of biochemical and molecular characteristics of Y. ruckeri isolates collected in north west Germany as a basis for strain differentiation. The isolates originated mainly from rainbow trout and were characterised by biochemical profiling, 16S rDNA sequencing, repetitive sequence-based PCRs, including (GTG)5-PCR, BOX-PCR, ERIC-PCR and REP-PCR, and pulsed-field gel electrophoresis (PFGE).

Results

In total, 83 isolates were characterised, including 48 isolates collected during a field study in north west Germany. All isolates were confirmed as Y. ruckeri by the API 20E system. Five isolates were additionally confirmed as Y. ruckeri by Y. ruckeri-specific PCR and 16S rDNA sequencing. Only 17 isolates hydrolyzed Tween 80/20. Sixty-six isolates (79.5%) were non-motile. Two different patterns were obtained by REP-PCR, five patterns by ERIC-PCR, four patterns by (GTG)5-PCR and three patterns by BOX-PCR. NotI-directed PFGE resulted in 17 patterns that differed from each other by 25–29 fragments. Isolates from the field study clustered together as PFGE type C. According to the results of API 20E, repetitive sequence-based PCRs and PFGE, these isolates could be subdivided into 27 different groups.

Conclusions

The detailed molecular and phenotypic characterisation scheme developed in this study could be used to help trace the dissemination of Y. ruckeri isolates, and thus may represent part of improved disease monitoring plans in the future.

Keywords:
Enteric Red mouth Disease; REP-PCR; ERIC-PCR; BOX-PCR; PFGE; Non-motile strains